The 31 May 2026 “Blue Micromoon”, the smallest full Moon of the year: online observation – 03:30 UTC
The “Blue Micromoon” is coming, the second full Moon of the month and the smallest of the year. The Virtual Telescope Project will broadcast the event live from Manciano, Italy, also featuring archival images of our natural satellite above some of Rome’s most iconic monuments.
The 31 May 2026 “Blue Micromoon”.
On May 31 at 08:45 UTC, the Moon will reach full phase for the second time during the same calendar month: a circumstance that, while not particularly rare, is relatively uncommon.
The interval between two full Moons averages about 29.5 days; consequently, there is usually only one full Moon per calendar month. A calendar year contains 12 complete lunar cycles, plus approximately 11 additional days. Because the synodic month is slightly shorter than the average calendar month, every two or three years a calendar year includes 13 full Moons.
In Anglo-Saxon folklore, this “extra” full Moon is known as a “Blue Moon”.
This mismatch between the calendar and lunar cycles manifests itself in two distinct ways. Since each season spans three months, there are generally three full Moons per season, though occasionally there are four. Likewise, although there is typically one full Moon per month, from time to time two full Moons occur within the same month.
A Blue Moon of one kind or the other takes place roughly once a year.
However, the upcoming full Moon on May 31 has another surprise in store: it will occur only 19 hours before the Moon reaches apogee — the point in its orbit farthest from Earth. As a result, it will be the most distant full Moon of 2026, and therefore also the smallest and faintest of the year. Specifically, its apparent disk will look approximately 6% smaller and about 10% dimmer than that of an average full Moon, differences that are subtle enough to likely go unnoticed by most observers.
One might therefore call it a “Blue Micromoon,” although the term has no scientific value.
On May 31 at 01:30 UTC, the Virtual Telescope Project will stream live images of the “Blue Micromoon,” captured by its robotic telescopes installed in Manciano, together with remarkable archival photographs of the Moon above the most famous monuments of Rome. To join the event, viewers simply need to visit the Virtual Telescope Project website at the scheduled date and time.
To join, you just need to enter, at the date and time above, our webTV page here!
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